The ability to understand quantitative information about probabilities is a critical component of health literacy. Although the probability of an event is only part of the multidimensional construct of perceived risk, probabilities are often used by experts and medical providers to convey risks to the public. Unfortunately, many people cannot understand or manipulate probabilities when they are presented as numbers. People of all educational levels are subject to cognitive biases when thinking about probabilities, and comprehension is further impaired by low educational level or numeracy. Among patients with low numeracy and educational level, comprehension is worst when probability information is presented in terms of probabilities or proportions, and best when it is presented through graphics that emphasize frequencies, such as grids of icons. However, not even graphical displays are successful with all audiences, and much previous research on them has been atheoretical. New research in cognitive psychology demonstrates that cognitive biases in probabilistic reasoning can be minimized or altered when probabilities are learned through experience (such as by drawing cards from a deck) rather than described as percentages (such as being told that 23 percent of the cards are face cards). Thus, we anticipate that we can improve comprehension and alter the effect on perceived risk by animating graphical displays to create virtual experiences of probabilities, and by encouraging users to interact with the displays and manipulate them. This study will (a) use qualitative methods with lay users to develop new computer-based graphical displays that incorporate animation and user interaction, (b) assess the effect of these displays in quantitative research on a large heterogeneous sample of users, and (c) explore the effects of numeracy and health literacy on comprehension of different display formats. The primary outcomes will be choice decisions between different risk scenarios, perceived risk, and quantitative comprehension. User satisfaction and interface usability will also be assessed. To enroll a diverse sample, we will recruit in both an on-line environment and from the Harlem Health Promotion Center, a national center for health promotion research. The interactive displays developed in this project have the potential to be applied to more comprehensive programs for health literacy education, tailored health and risk communication, shared medical decision-making, and patient decision support. [unreadable] [unreadable] [unreadable]